It's almost always good to set your reference to an object to nothing when you're done with it, but .Net's garbage collection should take care of that for you. If you have opened an RE object, you should usually call .CloseDown() on it (typically you do not call CloseDown on an object that was handed to you through an event though... the processing is expecting to get that object back!).

Thanks Jeff! I think that at some point I open secondary records and I am not closing them and it's creating some weird memory issues.